A model-driven simulation and requalification-decision framework for reuse of shelf-life-expired carbon-fibre prepregs in composite manufacturing

Circular composite manufacturing needs decision support that turns the uncertain condition of a recovered feedstock into production decisions. Shelf-life-expired carbon-fibre prepreg is a demanding case: each batch must be accepted, re-qualified under an adjusted process window, or rejected before it enters the line, and the information behind that decision is spread across organisations. This paper presents a model-based proof of concept of a simulation and requalification-decision framework. It couples an out-life degradation state model, a requalification and process-window decision layer, a mass-conserving material-flow model of eight unit operations and a first-time-right quality-risk module, and specifies the traceability service through which four partners share the records the decision needs. It is demonstrated on an Italian pilot reusing expired prepreg for drone components. The operational series and the out-life calibration data are synthetic, unit costs are illustrative and no part-level mechanical property was measured; 30 measured coupon-level requalification tests benchmark the out-life layer. Per 1000 kg of expired feedstock the reference case returns 149 kg of moulded output, 125 kg of it conforming, with the moulding conversion carried as a disclosed band of 0.21–0.79 (149–560 kg). For a proportional conversion, ratio results hold across that band: expired feedstock yields 84.0% of a virgin control, a value set by the admission rate, and a first-time-right cap reduces scrap by 40% for a 9% output loss under the stated parameters. In the measured tests, void content ordered the usability labels across four resin systems. Rising energy prices favour reuse in a directional screen.